Freight car loadings during an 18-week period at a port are:

a. Compute a linear trend line for freight car loadings. (Use of Excel’s Trendline, with display' Equation on chart option, is recommended).
b. Use the trend equation to predict loadings for weeks 19 and 20.
c. The manager intends to install new equipment when the volume reaches 700 loadings per week. Assuming the current trend continues, tire loading volume will reach that level in approximately what week?